Ballistic performance of ultralight multifunctional cellular sandwich plates with UHMWPE fiber metal laminate skins

While an ultralight sandwich construction with cellular core can be tailored to exhibit superior load-bearing capability and blast resistance, its ballistic performance is typically inferior to its equivalent monolithic counterpart. To improve the projectile penetration resistance while maintaining the capability of load bearing and blast mitigation, this work proposed a multifunctional sandwich plate with ultra-high molecular weight polyethylene (UHMWPE) fiber metal laminate (FML) skins and aluminum honeycomb core. A combined experimental and numerical approach was employed to quantify the ballistic performance, assess the penetration process, and reveal the underlying mechanisms of the novel sandwich construction. In addition to ballistic resistance, its performance under three-point bending as well as impulsive shock loading was also assessed for multifunctional applications. Relative to all-metallic honeycomb sandwich plate having identical areal density, incorporating UHMWPE composite layers into the skin improved significantly the penetration resistance: the failure mode of the laminate skin was changed from local shear-plugging to global dishing and cracking, enabling enhanced energy absorption of the thin metallic (titanium) layers. Moreover, the use of UHMWPE FML skin for sandwich construction led to not only significantly enhanced bending capacity but also reduced maximum deflection under impulsive shock loading. Hence, the proposed cellular sandwich plate with UHMWPE FML skins can be designed as ultralight multifunctional structure with simultaneous load-bearing and blast/ballistic resistant capabilities.